Conventional early enterprise systems supported one public switched telephone network (PSTN) or “trunk” per phone. However, newer enterprise telephone systems typically support a far larger number of telephones and connections to the PSTN. As a result, end-users may no longer be guaranteed placement of their outbound calls because all available trunks may be in use by other callers.
Traditional private branch exchanges (PBXs) provide for bundling groups of trunks together in order to support outbound callers. Most PBXs utilize an approach whereby a call agent, upon receiving a call request from an enterprise user, searches through all trunk resources to find an available trunk to place the outbound call. Voice over Internet protocol (VoIP) technologies also support such “route group” approaches.